Baby Weight Calculator

Estimate your baby's weight by week of pregnancy. Our fetal weight calculator provides an estimated weight range based on gestational age.

Estimate Fetal Weight

Enter your current week of pregnancy (8-42)

Understanding Fetal Growth

Fetal weight is an estimate based on averages. Actual weight can vary due to genetics, maternal health, and other factors. Ultrasounds provide the most accurate measurements.

Factors Influencing Fetal Weight

  • • Genetics: Parental size and ethnicity
  • • Maternal health: Diabetes, hypertension
  • • Nutrition: Maternal diet and weight gain
  • • Placental function: Efficiency of nutrient transfer
  • • Gender: Boys tend to be slightly heavier

Important Note

This calculator provides an estimate. Always consult your healthcare provider for accurate fetal growth assessment and medical advice.

Complete Guide to Fetal Weight and Growth

How Fetal Weight is Measured

During prenatal appointments, healthcare providers estimate fetal weight using various methods:

Fundal Height

Measurement from the top of the pubic bone to the top of the uterus. Generally, fundal height in centimeters correlates with gestational age in weeks (e.g., 28 cm at 28 weeks).

Ultrasound Biometry

Ultrasound measurements of specific fetal parts:

  • • Biparietal Diameter (BPD): Across the head
  • • Head Circumference (HC): Around the head
  • • Abdominal Circumference (AC): Around the abdomen
  • • Femur Length (FL): Length of the thigh bone

These measurements are then used in formulas to estimate fetal weight.

What if My Baby is Measuring Big or Small?

Variations in fetal weight estimates are common. Your doctor will consider these estimates along with other factors, such as your medical history, fundal height, and previous ultrasound scans. If there are significant concerns, further tests or monitoring may be recommended.

Possible Reasons for Larger Baby (LGA)

  • • Gestational diabetes
  • • Post-term pregnancy
  • • Maternal obesity
  • • Genetics (large parents)

Possible Reasons for Smaller Baby (SGA)

  • • Intrauterine growth restriction (IUGR)
  • • Placental problems
  • • Maternal high blood pressure
  • • Smoking or substance use
  • • Genetics (small parents)

💡 Key Takeaway

Fetal weight estimates are tools for monitoring, not definitive diagnoses. Regular prenatal care and discussions with your healthcare provider are crucial for understanding your baby's growth and well-being.